Power semiconductor elements such as IGBT (Insulated Gate Bipolar Transistor), power MOSFET transistor (Metal Oxide Semiconductor Field Effect Transistor), or MOSGTO (MOS Gate Turn-off Thyristor) are commonly known. These power semiconductor elements control electric power by inputting a signal for controlling the element into a gate to turn on/off the element.
The gate of power semiconductor element is connected with a wire formed on an insulating substrate. A control signal is inputted into the gate via the wire. If a plurality of power semiconductor elements is connected with the wire in parallel, it is typically assumed that those power semiconductor elements will be simultaneously turned on/off. However, if a switching speed of any one of those power semiconductor elements is different from that of others, the electric current is concentrated on a semiconductor element that turns on prior to other elements, or on a semiconductor element that delays in switching to off-state. Then the lifespan of such element will be more likely to be decreased, or such element will be more likely to be broken.
The switching time of semiconductor element is increased if the gate resistance is increased, and the switching time of semiconductor element is decreased if the gate resistance is decreased. Therefore, by increasing the gate resistance, it is possible to adjust the switching speed so that the difference in on/off timing between elements will be decreased. In some cases, in addition to the gate resistance of semiconductor element, a gate resistance component which is formed as a chip component is provided between the wire and the gate terminal, so that the switching times of each semiconductor element do not significantly vary due to variation in gate resistance within the semiconductor element.
Patent Literature 1 listed below describes a technique for adjusting gate resistance. In Patent Literature 1, a part of terminal connected to a gate electrode is formed with a material which has large specific resistance, and a sectional area size of that part or a length of that part is adjusted, thereby adjusting the gate resistance. Patent Literature 2 listed below describes a configuration example where a stack structure is formed on a sintered substrate, on which a glass powder paste and a metal paste are sintered.